The central nervous system (CNS) is a highly complex collection of specialized cells whose successful function relies on effective cellular communication to transport signal information across all the body's tissues and systems. Injury to these cells, whether through toxic molecules or processes, mechanical stresses, or age-related/genetic illnesses, leads to the breakdown of this communication and subsequent cell death. Regenerative medicine procedures to regain the functionality of the CNS after these insults is therefore of critical importance in the medical community. However, the fully developed CNS in the adult human body has limited capacity to regenerate tissues and to form these essential new cellular connections when lost. Among the great needs in this field are therapies to treat spinal cord injury (SCI) in order to prevent or reverse paralysis, novel treatments for stroke and neurodegenerative diseases, as well as strategies to recover the function of optic and auditory nerves. New therapies could profoundly enhance quality of life for individuals facing these problems and significantly reduce health care costs as well. For example, in the United States alone, SCI affects 12,000 individuals every year, and approximately 259,000 Americans currently live with the devastating effects of SCI. Novel therapeutic approaches to CNS regeneration will have significant impact on health care and patient well-being. In this renewal application three investigators, from the medical, chemical, and materials sciences, propose research to develop therapies for that could be used to prevent paralysis after spinal cord injury and also a different therapy that could be surgically implanted to reverse paralysis. The approach involves the use of especially designed molecules known as peptide amphiphiles that self-assemble in the spinal cord into nanofibers. These nanofibers carry biological signals that promote regeneration in the traumatized tissue, and biodegrade within weeks into harmless nutrients. The specific strategy involves the use of several peptide-based signals that emulate the effect of natural proteins, and also the delivery of genes that will lead to the production in the cord of regenerative growth factors. For acute injury the therapy takes the form of an injectable liquid, and for the chronic injury it consists of a pre-fabricated gel implant to be placed after removal of the glial scar in paralyzed patients. Both therapies will be tested in well established mouse models for spinal cord injury.